Influence of Rigid Ancillary Plates on Vortex-induced Vibration of Rectangular Box Girders

A comprehensive parametric numerical study is performed using the shear stress transport (SST) k-ω turbulence model to systematically investigate the effects of the installation configuration (leading edge (F), middle (M), trailing edge (B), F&B, and F&M&B) and the relative length ratio (L/D = ۰.۲۵–۱.۵) of rigid ancillary plates on the single-degree-of-freedom cross-flow vortex-induced vibration (VIV) of a ۱۰:۱ aspect-ratio rectangular box girder. The results indicate that the configuration and length of the ancillary plate substantially affect the vibration response of the box girder. Installing the plate at F or in combinations with F (F, F&B and F&M&B) significantly increases vibration, and the vibration amplitude increases with plate length. Installing ancillary short plates (L/D ≤ ۰.۵) at M and B results in no vibration, whereas using long plates (L/D ≥ ۱) at M leads to strong vibration. Flow field analysis indicates that the ancillary plate modifies the shear layer’s separation and reattachment, as well as vorticity accumulation-release mechanisms, thereby affecting the generation and evolution of the excitation force and the vibration response. The vibration amplitude is strongly correlated with fluctuations in aerodynamic force. The ratio of the lift coefficient’s dominant frequency to the structural natural frequency approaches ۱ within the lock-in range, whereas galloping characteristics are observed at high reduced velocities and for long plates.

Keywords:

Vortex-induced vibration , Rectangular box girders , Ancillary plates , Flow fields , galloping